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REFRACTION OF LIGHT
(P 33 01)

Apparatus:
GSN 246
POG 465
POG 461
POG
550.01
KAL
60/5A

Adhesive Magnetic Board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Cuvette

1
1
1
1

Connecting lead
Power supply

2
1

Beaker glass

1

Procedure:



Fill the cuvette with water.
Setup the ray box as shown
A light ray emitted by the ray box hits the surface where the air meets the
water at an angle of incidence of about 30°. It may, on the one hand, be
observed that the light is refracted toward the perpendicular and, on the other,
that it is partially reflected from this surface.
The light ray hits the surface where the water meets the air at an angle of
incidence . It may be observed that the light ray is refracted from the
perpendicular at angle and partially reflected at angle .The reflected ray of
light returns to the surface where the water meets the air. Here again refraction
from the perpendicular and partial reflection occur.
In addition, it may be seen that the ray proceeding from the light and the one
leaving the cuvette below are shifted. The beaker with water represents a plate
with parallel faces.

Optics Panel Type |

1


TOTAL REFLECTION IN WATER
(P 33 02)

Apparatus:
GSN 246

POG 465
POG 461
POG
550.01
KAL
60/5A





2

Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Cuvette

1
1
1
1

Connecting lead
Power supply

2
1

Beaker glass

1

The cuvette is filled with water. The water may be colored using fluorescein
sodium.
The transition from water to air is observed.
The angle of incidence is smaller than the critical angle for water. Thus,
partial reflection (ray a) and refraction from the perpendicular (ray b) occur.

| Optics Panel Type




The ray box is turned so that the angle of incidence is greater than the critical
angle for water.
No refraction occurs, merely complete reflection – total reflection.
The surface of the water acts as a mirror.

Optics Panel Type |

3


CALCULATING THE INDEX OF
REFRACTION
(P 33 03)

Apparatus:
GSN 246

POG 465
POG 461
POG
400.03
KAL
60/5A





Adhesive magnetic
board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Optical disc

1

Connecting lead
Power supply

2
1

Whiteboard marker
Ruler

1
1

The ray box is placed so that the angle of incidence is 30°.
The angle of refraction is measured along with the distances x and y.
The experiment is repeated at an angle of incidence 1 = 60° and the
corresponding results are noted:

x = 7,5 cm x1 = 12,9 cm

4

1
1
1

| Optics Panel Type


y = 5,1 cm y1 = 8,8 cm

The ratio of the two distances to each other is constant. This value is termed
the index of refraction n.
It may be furthermore shown that:
sin 30° : sin = sin 60° : sin 1 = 1,47
It is not difficult to deduce from this the Law of Refraction: sin a : sin b = n
Using the equation 1 : sin = n the critical angle is found to be about = 43°,
which matches up quite well with the results of the experiment.

Optics Panel Type |

5

TOTAL REFLECTION IN GLASS
(P 33 04)

Apparatus:
GSN 246
POG 465
POG 461
POG 400.03
POG 251
KAL 60/5A







Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Optical disc
Semicircle, lens model
Connecting lead
Power supply
Whiteboard marker
Ruler

Setup the ray box and the semicircle lens model on the optical disk as shown.

The light ray emitted by the ray box is to be aimed directly at the center of the
lens. This may be checked by means of the reflected ray.
The angle of incidence measured must correspond exactly to the angle of
reflection measured.
The light ray hits the lens at an angle of incidence of 0at first. This light ray
corresponds to the perpendicular which is drawn in.
Then the angle of incidence is set again to different values: 1 = 10°, 2 = 20°
and 3 = 30°. The partially reflected rays are observed along with the refracted
ones.

Angl

10°
20

e of

6

1
1
1
1
1
2
1
1
1

| Optics Panel Type

30

40

43

45°

50°

60°


°

incidence 

°

°

°

18

Angl

–

–

–

23 47 75 90
°
°
°
°
refraction 
Dispersion - Ray brushes Total reflection
spectrum surface = 90°
e of

°

At an angle of incidence of = 40° and an angle of refraction of about 75°,
color dispersion may be clearly seen.
At an angle of incidence of about = 43° the refracted ray brushes the
surface = 90°). Once the critical angle is reached, only the reflected ray
remains – total reflection.

Optics Panel Type |

7


TOTAL REFLECTION IN A SEMI-CIRCLE
BODY
(P 33 05)

Apparatus:
GSN 246
POG 465
POG 461
POG 400.03
POG 251
KAL 60/5A

8

Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Optical disc
Semicircle, lens model
Connecting lead
Power supply

1
1
1
1
1
2
1



The ray of light emitted by the ray box hits the acrylic glass object at a right

angle. Due to total reflection, it then travels along the boundary between the
acrylic glass and the air in a semi-circular direction through the object and
leaves it at the bottom end (light beam, aperture angle). The aperture angle is
determined by the manner in which the thin, slightly divergent light beam
enters the object. The individual light rays follow slightly different paths
through the acrylic glass object.



When the light ray is moved farther inside, the path of the light can be seen
more clearly. The effect caused by total reflection along the surface where the
acrylic glass meets the air can now be easily recognized.

| Optics Panel Type


BASIC PRINCIPLE OF A
PHOTOCONDUCTOR
(P 33 06)

Apparatus:
GSN 246
POG 465
POG 461
POG 240.03
KAL 60/5A







Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
C shaped lens, Photoconductor
model
Connecting lead
Power supply

1
1
1
1
2
1

The light ray emitted by the ray box hits the end of the C-shaped lens at a right
angle. Due to total reflection, the light ray travels along the surface where
acrylic glass meets the air.
The effect caused by total reflection along the surface where acrylic glass
meets the air can be easily recognized.
Light can be transported in a thin glass body for long distances and even along
a crooked path in such a manner. This is the basic principle of a
photoconductor.
The refraction of the light ray away from the perpendicular can be observed
where the light leaves the acrylic glass object.

Optics Panel Type |

9


PHOTOCONDUCTOR, FLEXIBLE
(P 33 07)

Apparatus:
GSN 246
POG 465
POG 461
POG 245
KAL 60/5A






Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Fiber optic, model
Connecting lead
Power supply

1
1
1
1

2
1

The model photoconductor is attached to the side of the ray box with fan and
circular aperture. The light from the bulb is conducted along the flexible
photoconductor for some distance and even along a crooked path.
The spherically shaped opening at the end of the photoconductor causes a lens
effect resulting in a distinct light cone at the immediate end of the
photoconductor.
With the aid of this photoconductor, light may be conducted into a small box for
example.

10 | Optics Panel Type


THE PLANE PARALLEL PLATE
(P 33 08)

Apparatus:
GSN 246
POG 465
POG 461
POG 311
KAL
60/5A

Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Prism, trapezoid

Connecting lead
Power supply

1
1
1
1
2
1

Whiteboard marker
Ruler

1

Optics Panel Type | 11




The light ray enters the surface of the trapezoid at a right angle, passes
through the acrylic glass and leaves it without being refracted. This ray path is
drawn in.



The trapezoid object serving as a plane parallel plate is brought into the second
position as shown.

The following phenomena may be observed:

 Reflection (light ray 1) and refraction toward the perpendicular occur where air
and acrylic glass meet.
 Refraction from the perpendicular occurs where acrylic glass meets the air. The
light ray leaving the plane parallel plate is displaced yet parallel to the ray
entering. Part of the light is reflected at point 2.
 This reflected light ray is refracted from the perpendicular where the acrylic
glass meets the air (light ray 2).
The two light rays travel parallel to each other.
The greater the inclination of the plane parallel plate, the greater the angle of
incidence. The greater the angle of incidence, the greater the parallel
displacement of the light ray which is refracted twice.

REFRACTION OF LIGHT IN A PRISM
(P 33 09)

Apparatus:
GSN 246
POG 465
POG 461
POG
310.03

Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 1 and 2 slits
Prism, right angle

1
1
1

1

Connecting lead

2

12 | Optics Panel Type


KAL
60/5A

Power supply

1

Whiteboard marker
Ruler

1



The prism with a right angle and equal sides is positioned as shown in the
diagram.
At first refraction and partial reflection at the refracting surfaces can be
observed.
 The place where the light ray hits the surfaces is marked, and the outline of the
prism and the position of the two perpendiculars are drawn in. This shows more
distinctly the refraction toward the perpendicular where the ray passes from an

optically less to an optically more dense medium and the refraction from the
perpendicular in the opposite case.



The prism is then turned in a clockwise direction. The partially reflected rays
become brighter and the refracted ray turns downward; deviation as a whole
increases. The critical case is reached when the ray brushes the surface.

DEVIATING PRISM

(P 33 10)

Apparatus:
GSN 246
POG 465

Adhesive magnetic
board
Ray box, 6V 20W

1
1

Optics Panel Type | 13


POG 462
POG 310.03
POG 220.01

POG 220.02
KAL 60/5A

Diaphragm 3 and 5 slits
Prism, right angle
Color filter red
Color filter blue
Connecting lead
Power supply

1
1
1
1
2
1



The prism with a right angle and equal sides is positioned about 20 cm from the
ray box so that one of the shorter sides is perpendicular to the light rays
reaching it.



The hypotenuse of the prism (boundary surface between acrylic glass and air)
acts a plane mirror due to total reflection. The approaching light rays change
direction by a total of 90°.

INVERTING PRISM

(P 33 11)

14 | Optics Panel Type


Apparatus:
GSN 246
POG 465
POG 462
POG 310.03
POG 220.01
POG 220.02
KAL 60/5A

Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 3 and 5 slits
Prism, right angle
Color filter red
Color filter blue
Connecting lead
Power supply

1
1
1
1
1
1

2
1



The prism with a right angle and equal sides is positioned about 20 cm from the
ray box so that its hypotenuse is perpendicular to the light rays hitting it. The
three parallel light rays enter the prism in its top half.



Being totally reflected twice from the shorter sides of the right-angled prism
with equal sides, the rays leaving it do so parallel to the ones entering it, yet in
the opposite direction. In addition, because the three rays are totally reflected
twice, their order is reversed upon leaving. The two short sides of the prism act
as two plane mirrors situated at right angles to each other.

Note:
An image may be entirely reversed (i.e. up <--> down, left <--> right) by using
two prisms placed back to back and including a right angle between them.

Optics Panel Type | 15


TORRICELLI'S PRISM
Apparatus:
GSN 246
POG 465
POG 462
POG 310.03

POG 220.01
POG 220.02
KAL 60/5A



Adhesive magnetic board
Ray box, 6V 20W
Diaphragm 3 and 5 slits
Prism, right angle
Color filter red
Color filter blue
Connecting lead
Power supply

1
1
1
1
1
1
2
1

The prism is positioned so that the light ray entering it and its hypotenuse are
parallel to each other.
During the transition from air to acrylic glass, the light ray entering is partially
reflected and partially refracted toward the perpendicular. The entering and the
reflected ray are at right angles to each other. The refracted light ray is totally
reflected by the hypotenuse and then refracted from the perpendicular by the

short end on the other side as the ray passes from acrylic glass to air. The light
ray entering and the one leaving are parallel to each other but displaced.

Note:
Torricelli's Prism is used to reverse images when the course of the light rays is
to remain unchanged and the top is merely to be exchanged with the bottom.

16 | Optics Panel Type